There are two phases to the fix. One is available immediately, but new hardware is necessary next year.

Volkswagen has finally worked out a satisfactory way to clean up some of its polluting diesel engines. The Environmental Protection Agency and California Air Resources Board have already approved the repair after VW demonstrated that the mend didn’t “affect vehicle fuel economy, reliability, or durability.” The EPA and CARB also conducted independent tests that checked whether the fix performed as the automaker promised.

VW’s newly certified fix only works on so-called Generation 3 models with the 2.0-liter turbocharged diesel four-cylinder. These vehicles are the 2015 model year Beetle, Beetle Convertible, Golf, Golf SportWagen, Jetta, Passat, and Audi A3. These owners still have the choice for VW Group to buy back their model, but this option also gives them the opportunity to repair the automobile.

VW will conduct the fix in two phases. A software update now available to owners removes the defeat device software and “directs the emission controls to function effectively in all typical vehicle operation,” according to the EPA and CARB. A second repair arrives in about a year and involves another software change, plus a new diesel particulate filter, diesel oxidation catalyst, and NOx catalyst. The agencies says this equipment is “needed to maintain vehicle reliability and emissions performance over time.”

“We will now notify eligible customers in the United States that they can receive phase one of this modification at dealerships free of charge as soon as possible. Volkswagen continues to work closely with EPA and CARB to reach an agreement on approved emissions modifications for other affected 2.0L TDI vehicles as quickly as possible,” VW said in a statement.

On October 25, 2016, the Court entered a $14.7 billion partial settlement with Volkswagen to resolve alleged Clean Air Act violations from the sale of 2.0 liter diesel vehicles that were equipped with software designed to cheat on federal emissions tests. The settlement allows VW to propose and seek EPA and CARB approval for technical remedies to address the pollution violations. Today, EPA and CARB are approving a remedy proposed by Volkswagen that will reduce the excess NOx emissions from the Generation 3 diesel 2.0 liter vehicles. With today’s approval, VW can offer vehicle owners the choice to keep and fix their car, or to have it bought back. The test data and technical information VW submitted to EPA and CARB demonstrated that the emissions modification being approved today will not affect vehicle fuel economy, reliability, or durability. EPA and CARB confirmed those conclusions through independent testing and analysis at their own laboratories.

Today’s approval means that VW can now notify customers that the emissions modification is available and begin performing the modification at its dealerships. The approved modification requires both software and hardware replacement, and will take place in two phases. The first phase involves a software change that is available to customers now. The second phase involves further software changes as well as hardware changes that are not yet available. In the first phase, VW will remove the defeat device software and replace it with software that directs the emission controls to function effectively in all typical vehicle operation. The second phase will start about a year from now when VW will install more software updates as well as a new diesel particulate filter, diesel oxidation catalyst, and NOx catalyst, all needed to maintain vehicle reliability and emissions performance over time.